简介
log4cpp是个基于LGPL的开源项目，是基于优秀的日志处理跟踪项目Java语言的log4j移植过来的。
优点
- 提供应用程序运行上下文，方便跟踪调试
- 可扩展的、多种方式记录日志，包括命令行、文件、回卷文件、内存、syslog服务器、Win事件日志等
- 可以动态控制日志记录级别，在效率和功能中进行调整
- 所有配置可以通过配置文件进行动态调整
- 多语言支持，包括Java（log4j），C++（log4cpp、log4cplus），C（log4c），python（log4p）等
配置及使用
- 包含头文件
#include <log4cpp/Category.hh>
#include <log4cpp/FileAppender.hh>
#include <log4cpp/PatternLayout.hh>
#include <log4cpp/OstreamAppender.hh>
- 初始化附加目的地(appenders)
// 输出到std::cout
log4cpp::Appender *appender = new log4cpp::OstreamAppender("root", &std::cout);
// 输出到log文件
log4cpp::Appender *appender = new log4cpp::FileAppender("root", "test.log");
- 设置输出格式(layout)
log4cpp::PatternLayout *patternLayout = new log4cpp::PatternLayout();
patternLayout->setConversionPattern("%d [%p] - %m%n");
appender->setLayout(patternLayout);
其他相关可以自己设置相关提示信息
- %% - a single percent sign
- %c - the category
- %d - the date\n Date format: The date format character may be followed by a date format specifier enclosed between braces. For example, %d{%H:%M:%S,%l} or %d{%d %m %Y %H:%M:%S,%l}. If no date format specifier is given then the following format is used: "Wed Jan 02 02:03:55 1980". The date format specifier admits the same syntax as the ANSI C function strftime, with 1 addition. The addition is the specifier %l for milliseconds, padded with zeros to make 3 digits.
- %m - the message
- %n - the platform specific line separator
- %p - the priority
- %r - milliseconds since this layout was created.
- %R - seconds since Jan 1, 1970
- %u - clock ticks since process start
- %x - the NDC
- %t - thread name
- 设置类别(categories)和优先级(priority)
log4cpp::Category &root = log4cpp::Category::getRoot();
root.setPriority(log4cpp::Priority::NOTICE);
root.addAppender(appender);
- 优先级：NOTSET < DEBUG < INFO < NOTICE < WARN < ERROR < CRIT < ALERT < FATAL = EMERG
- 定义一个宏定义
// 使用 LOG(WARN) << "message" 的格式来记录日志
#define LOG(__level) log4cpp::Category::getRoot() << log4cpp::Priority::__level << "\n\t" << __FILE__ << " " << __LINE__ << ": "
- 在文件中记录打印日志
...
LOG(INFO) << "Device open success.";
...
LOG(ERROR) << "Device open failed.";
...
设置优先级以后只有高于所设置优先级的信息会被记录下来，因此可以通过宏定义来实现Debug和Release不同的信息优先级。
- 运行结果示例
2017-09-12 09:31:28,317 [INFO] -
/home/jiang/git/aero-node/an-core/example/qa_voice_capture.cc 36: Device open success.
2017-09-12 09:31:28,318 [INFO] -
/home/jiang/git/aero-node/an-core/example/qa_voice_capture.cc 59: Initialize hardware parameter success.
2017-09-12 09:31:28,318 [INFO] -
/home/jiang/git/aero-node/an-core/example/qa_voice_capture.cc 70: Set access type success.
- 其他
- 可以将初始化配置自己封装到一个logger.h文件中，以后再需要使用直接include即可
